Upon commencing bypass, it was noticed that the CDIinline blood gas monitoring device was showing a lower pO2 than expected(around 17), with an FiO2 set at 75%. Gases were taken to calibrate the device,which showed it was accurate, so Fi02 was increased to 90%. ACT was checked and came back at 365, so 10,000iu of heparin was given and a repeat ACT gave aresult of mid 400's.

During this time, the cross-clamp had been applied,cardioplegia given and the first anastomosis bypass graft had commenced.The pre-membrane pressure alarmed, indicating an oxygenator issue, so another perfusionist was called to assist, anaesthetist was informed that there may be an oxygenator issue, whilst checks were made to see if anything obvious couldbe wrong, no line kinks were found, and the gas line was changed out. It was determined that there was a problem with the oxygenator as the pre-membrane pressure continued to increase, post-membrane pressure decreased, and pO2 levels were also decreasing, so the surgeon was informed. It was decided that we would remove the cross-clamp, stay at 32 degrees and come offbypass to then change out the oxygenator. The pre-membrane pressure was preventing full flow (5.3L/min), and the patients MAP was in the low 30's, despite giving a large amount of 100mc/ml Phenylephrine. This pressure alarm was overridden so we could achieve full flow on bypass and gain stability to then come off. NIRS were also then applied to monitor head saturation, which were in the 60's and remained so throughout therest of the operation .Once off bypass, 3 perfusionists worked together to change out the oxygenator,de-air the circuit and commence bypass. This was done in 6 minutes.

Bypass was commenced, full flow achieved, pre and post-membrane pressures within normal range, and pO2 also within normal range with an acceptable FiO2. Blood gases were taken to calibrate the CDI, and all agreed to continue as planned. Cross-clamp reapplied, cardioplegia given and grafting commenced. Upon rewarming, pO2 levels started to decrease and were not greatly improving when increasing FiO2. When the cross-clamp was removed, I had reached using an FiO2of 90%, the anaesthetist was informed so we could prepare to put the lungs onas soon as possible, and the surgeons were then also informed. The lungs were put on to finish the top ends of each anastomosis with a view of coming off bypass as soon as possible. Bypass was ended with FiO2 running at 100% and a pO2 of 13 Both oxygenators have been retained to be sent to the manufacturer for testing. Patient had no comorbidities prior to surgery or any known coagulopathy issues. First bypass run was 54 mins, second bypass run 74 mins.

• The second oxy did have an increasing transmembrane pressure but not to the same extent as the first.
• Gas flow was checked and attached directly to test flow which was adequated so no gas issue.
• Baseline ACT was over 400, the first ACT on bypass was 360, and then ACT’s remained therapeutic for the rest of the case (>400), so FFP  wasn’t considered.
• There was no baseline TEG done for this patient so unable to ascertain coagulopathy.
• Patient has now been extubated with no ill effects